Thanks to recent advancement of technologies, digital still cameras (which are often called simply “digital cameras”) have become rapidly popular nowadays and more and more people now use a cellphone with camera commonly. Under circumstances such as these, there is an increasing demand for techniques for further reducing the size of a camera device in one way or another. And the camera devices are also required to capture an image of even higher quality.
Generally speaking, a camera device has a lens unit consisting of multiple lenses for use to produce an image on the image capturing plane of an image sensor. The performance of a camera device (such as its resolution) depends heavily on how precisely the barrel and other parts of the lens unit can be designed and how accurately the lenses can be assembled together into the lens unit. That is why when the lens unit is made, a good care should be taken of how to bond those lenses and how to make adjustments on the lenses being assembled together.
Patent Document No. 1 discloses how to make an integral lens block by combining a number of lenses together with their optical axes aligned with each other. Hereinafter, such a conventional lens block making method as disclosed in Patent Document No. 1 will be described with reference to FIGS. 23 and 24.
FIG. 23 is a perspective view showing the procedure of inserting lenses into a fixing jig one after another. FIG. 24 is a cross-sectional view of the lenses that have been inserted into the fixing jig as viewed on a plane on which the optical axis of the lenses is defined. As shown in FIG. 23, first, second, third and fourth lenses 810, 820, 830 and 840 are inserted in this order into a fixing jig 710. As a result, the respective lenses are supported by the fixing jig 710 so as to be stacked one upon the other as shown in FIG. 24.
In such a state, an adhesive is injected through first, second, third and fourth sets of through holes 711A, 711B, and 711C, 712A, 712B and 712C, 713A, 713B and 713C, and 714A, 714B and 714C, all of which run from the outer side surface through the inner side surface of the fixing jig 710, thereby bonding the first, second, third and fourth lenses 810, 820, 830 and 840 together. In this manner, a lens block in which those four lenses are combined together is obtained. According to Patent Document No. 1, by moving the lenses with jig bars inserted into the respective through holes before these lenses are bonded together with the adhesive, the degrees of eccentricity of the lenses can be adjusted. The lens block that has been assembled in this manner will be secured to the barrel of a camera device.
Patent Document No. 2 discloses a lens unit in which when lenses are inserted into a barrel, jig bars are also inserted into multiple through holes that run through the side surface of the barrel to move the lenses, thereby adjusting the degrees of eccentricity of the lenses.
On the other hand, Patent Document No. 3 discloses a lens unit that can easily adjust the degrees of eccentricity by using lenses with a projection on their side surface. According to Patent Document No. 3, the barrel has notches and the lenses are arranged so that their projections are inserted into the notches. The positions of the lenses are adjusted with those projections, the lenses are fixed onto the barrel, and then unnecessary projections are cut off.